3-D focusing inversion of CSAMT data

We present a method for the solution of 3-D controlled source magnetotelluric (CSAMT) inverse problems. The inverse problem is formulated as the minimization of a Tikhonov parametric functional with a focusing stabilizer. Observed CSAMT apparent resistivities are converted to log-anomalous apparent resistivities, which are linearly connected to anomalous currents via the integral equation. We apply the Born iterative method to solve this integral equation, using a focusing regularized inversion. The focusing is based on a specially selected stabilizing functional which minimizes the area where strong model parameters variations and discontinuities occur. The method is illustrated using examples of 3-D inversion of model CSAMT data, and with a real data example.